The present invention is directed to a nut and retainer fastener assembly for securing the nut to a panel or the like, and to a method of fastener assembly manufacture.
U.S. Pat. No. 3,496,980 discloses a nut and retainer fastener assembly in which a flange nut is secured to the upper portion or wall of a U-shaped sheet metal retainer. The upper wall of the retainer is embossed during the forming operation to provide clearance for the nut flange. The forward edge of the upper wall terminates in a V-shaped bend that extends laterally across the retainer and functions to expand the retainer during installation over the edge of a panel. The corners of the nut are staked, so that the embossed portion of the retainer is captured between the nut flange and the stakes to mount the nut on the retainer. The sheet metal retainers are formed and the nuts are assembled to the retainers in a progressive blanking, bending and assembly operation.
Embossment of the portion of the retainer on which the nut is mounted subjects the retainer to severe dimensional distortions due to stretching of material, and increases tooling cost and tooling wear. Manufacturing techniques are employed that result in excessive material waste. Furthermore, distortion of the retainer makes it difficult to retain close tolerances in the assembly. The fastener design and associated manufacturing tooling are not readily modifiable for different nut sizes and/or different panel thicknesses. Furthermore, the elongated contact area between the retainer and the panel during assembly, together with stiffness of the retainer, can make it difficult to install the nut and retainer fastener assembly onto a panel. It is a general object of the present invention to provide a nut and retainer fastener assembly, and a method of manufacture, that address and ameliorate one or more of these deficiencies in the prior art.
A fastener assembly in accordance with a first aspect of the present invention includes a retainer having first and second wall portions and a third wall portion interconnecting adjacent ends of the first and second portions such that the first portion overlies and is spaced from the second portion. The first wall portion of the retainer has a forward edge remote from the third wall portion. This forward edge includes laterally spaced tabs at opposed ends of the forward edge, with the tabs extending toward the second wall portion and having free ends spaced from the second portion of the retainer. A flange nut is mounted on the first wall portion of the retainer, and has a flange disposed within the first portion and spaced from the second portion.
The tabs preferably have straight edges contiguous with the forward edge of the first wall portion and oriented at an acute angle to the first portion. These angulated edges on the tabs facilitate installation of the assembly onto a panel by providing essentially point-areas of contact between the retainer and the edge of the panel, and by camming the first wall portion of the retainer away from the second wall portionxe2x80x94i.e., opening the retainerxe2x80x94during installation onto the panel. In the preferred embodiment of the invention, the acute angle between the forward edges of the tabs and the edge of the first wall portion of the retainer is in the range of zero to 90xc2x0, and most preferably about 60xc2x0. The second wall portion of the retainer has an opening for extending a threaded fastener into the nut, and preferably has a locating tab adjacent to such opening for locating the retainer with respect to an opening in the panel when the assembly is secured to the panel. An opening or cut-out in the first and third wall portions of the retainer preferably increases flexibility of the retainer, further to reduce installation force during assembly onto a panel. The flange nut preferably comprises a hex nut having stakes at less than all corners of the nut, preferably at two or three corners of the nut, leaving the remaining corners for use in disassembly of a fastener from the nut.
A fastener assembly in accordance with another aspect of the present invention includes a one-piece U-shaped sheet metal retainer having first and second planar wall portions and a third wall portion interconnecting adjacent ends of the first and second wall portions such that the first wall portion overlies and is spaced from the second wall portion. The first wall portion of the retainer has a forward edge with laterally spaced tabs extending toward the second wall portion with free ends spaced from the second wall portion. The free ends are flat and are parallel to the first wall portion. A flange nut is mounted on the first wall portion of the retainer. The flange nut has a flange disposed within the first wall portion and spaced from the second wall portion. The tabs extend from the first wall portion by an mount sufficient that the assembly can be secured over an edge on a panel without interference between the panel edge and the nut flange.
A method of making a fastener assembly in accordance with a third aspect of the present invention includes forming a metal retainer in a progressive blanking and bending operation. The metal retainer is U-shaped, having first and second flat wall portions interconnected by a third wall portion. The first wall portion has an opening and a forward edge with laterally spaced tabs extending toward the second wall portion at opposed ends of the forward edge. The free ends of the tabs are spaced from the second wall portion. A flange hex nut is secured within the opening in the first wall portion, preferably by staking at less than all corners of the nut.